Page 210 - Plant design and economics for chemical engineers

184 PLANT DESIGN AND ECONOMICS FOR CHEMICAL ENGINEERS

TABLE 18
Lang multiplication factors for estimation of
fixed-capital investment or total capital investment
Factor x delivered-equipment cost = fixed-capital investment
or total capital investment for major additions to an existing
plant.
I Factor for
I I Total capital
Fixed-capital
Type of plant investment investment I
----I I I
Solid-processing plant I 3.9 I 4.6 \
Solid-fluid-processing plant 4.1 4.9
Fluid-processing plant 4.8 5.7

process plant may be obtained by multiplying the basic equipment cost by some
factor to approximate the capital investment. These factors vary depending
upon the type of process plant being considered. The percentages given in
Table 17 are rough approximations which hold for the types of process plants
indicated. These values, therefore, may be combined to give Lang multiplication
factors that can be used for estimating the total direct plant cost, the fixed-capital
investment, or the total capital investment. Factors for estimating the fixed-
capital investment or the total capital investment are given in Table 18. It
should be noted that these factors include costs for land and contractor’s fees.
Greater accuracy of capital investment estimates can be achieved in this
method by using not one but a number of factors. One approach is to use
different factors for different types of equipment. Another approach is to use
separate factors for erection of equipment, foundations, utilities, piping, etc., or
even to break up each item of cost into material and labor factors.? With this
approach, each factor has a range of values and the chemical engineer must rely
on past experience to decide, in each case, whether to use a high, average, or
low figure.
Since tables are not convenient for computer calculations it is better to
combine the separate factors into an equation similar to the one proposed by
Hirsch and Glazier+
C,=f,[W +.fF+fp+.fJ+~i+~] (4)

tFurther discussions on these methods may be found in W. D. Baasel, “Preliminary Chemical
Engineering Plant Design,” American Elsevier Publishing Company, Inc., New York, 1976; S. G.
Kirkham, Preparation and Application of Refined Lang Factor Costing Techniques, AACE Bul.,
15(5):137 (Oct., 1972); C. A. Miller, Capital Cost Estimating-A Science Rather Than an Art, Cost
Engineers’ Notebook, AXE A-1666 (June, 1978).
$J. H. Hirsch and E. M. Glazier, Chem. Eng. Progr., 56(12):37 (1960).